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Thermal Performance and Mechanics Characteristic for Double Layer Microchannel Heat sink

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Journal of Thermal Science 2019年第2期28卷 271-282页

作者： XU Yupeng GONG Liang LI Yongtong BAI Zhang XU Minghai Department of Energy & Power Engineering China University of Petroleum (East China)

Double layer micro-channel heat sink(DLMCHS) has been widely used in various electronic devices; however, the existence of the nonuniform thermal strain distribution in actual operation has adverse effect on the overall stability. In this paper, two optimized designs of DLMCHS with cutting baffles on top and bottom layers are presented based on the traditional DLMCHS. The heat transfer and thermal stress performance are numerically analyzed and compared with the traditional DLMCHS. The results indicate that cutting baffles of micro-channels remarkably improves heat transfer and thermal stress performance. The optimized design with cutting baffles on the bottom layer decreases thermal strain but deteriorates heat transfer performance. The model with cutting baffles on the top layer has better combined thermal strain and heat transfer performance, which reduces thermal strain by about 1.5 times and enhances heat transfer by about 26.5%. For the design with cutting baffles on the top board, adding metal foam in the inlet collector can decrease the total minimum thermal strain by 51.4% and maximum temperature by 1.4 K, and increase the Nusselt number by 15%. These results indicate that DLMCHS with cutting baffles on the top layer has great potential for thermal managements on electronic devices with high power density.

关键词： double layer micro-channel heat sink thermal strain thermal performance optimized design

Targeted energy transfer of a parallel nonlinear energy sink

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Applied Mathematics and Mechanics(English Edition) 2019年第5期40卷 621-630页

作者： Yimin WEI Sha WEI Qianlong ZHANG Xinjian DONG Zhike PENG Wenming ZHANG State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong University

A parallel nonlinear energy sink(NES) is proposed and analyzed. The parallel NES is composed of a vibro-impact(VI) NES and a cubic NES. The dynamical equation is given, and the essential analytical investigation is carried out to deal with the cubic nonlinearity and impact nonlinearity. Multiple time-scale expansion is introduced, and the zeroth order is derived to give a rough outline of the system. The underlying Hamilton dynamic equation is given, and then the optimal stiffness is expressed. The clearance is regarded as a critical factor for the VI. Based on the periodical impact treatment by analytical investigation, the relationships of the cubic stiffness, the clearance, and the zeroth-order attenuation amplitude of the linear primary oscillator(LPO) are obtained.A cubic NES under the optimal condition is compared with the parallel NES. Harmonic signals, harmonic signals with noises, and the excitation generated by a second-order?lter are considered as the potential excitation forces on the system. The targeted energy transfer(TET) in the designed parallel NES is shown to be more e?cient.

关键词： targeted energy transfer (TET) nonlinear energy sink (NES) nonlinear vibration absorber impact vibration reduction

Energy harvesting via nonlinear energy sink for whole-spacecraft

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Science China(Technological Sciences) 2019年第9期62卷 1483-1491页

作者： ZHANG YeWei LU YanNan CHEN LiQun Faculty of Aerospace Engineerings Shenyang Aerospace UniversityShenyang 110136China School of Science Harbin Institute of TechnologyShenzhen 518055China

This paper presents nonlinear energy sink with giant magnetostrictive-piezoelectric material for energy harvesting of the wholespacecraft vibration reduction system. The whole-spacecraft vibration attenuation system can effectively reduce vibration and achieve self-tuning enhanced energy harvesting range. The open-circuit voltage generated at low frequency is affected by the magnetic field force, alternating magnetic field and relative displacement. In order to acquire a steady periodic solution of the energy harvesting system, a combination of the harmonic balance method and pseudo arc length continuation technique is *** numerical outcomes are consistent with the analytical outcomes in a certain range, which also proves the accuracy and reliability of the results. The amplitude and voltage of the energy harvesting system are analyzed by parameters such as cubic stiffness, viscous damping, and external excitation acceleration. In addition, this paper provides a new idea for broadband energy harvesting.

关键词： nonlinear energy sink giant magnetostrictive-piezoelectric material pseudo arc length continuation technique energy harvesting

Thermal analysis of an LED module with a novelly assembled heat pipe heat sink

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Journal of Central South University 2017年第4期24卷 921-928页

作者： TANG Yong CHEN Qiu GUAN Wo-huan LI Zong-tao YU Bin-hai YUAN Wei School of Mechanical and Automotive Engineering South China University of Technology Guangzhou 510640 China

This work aims to improve the thermal performance of a light emitting diode(LED) module by employing a novelly assembled heat pipe heat sink. The heat pipe was embedded into the heat sink by a phase change expansion assembly(PCEA) process, which was developed by both finite element(FE) analysis and experiments. Heat transfer performance and optical performance of the LED modules were experimentally investigated and discussed. Compared to the LED module with a traditionally assembled heat pipe heat sink, the LED module employing the PCEA process exhibits about 20% decrease in the thermal resistance from the MCPCB to the heat pipe. The junction temperature is 4% lower and the luminous flux is 2% higher. The improvement in the thermal and optical performance is important to the high power LED applications.

关键词： light emitting diode (LED) phase change assembly heat pipe heat sink thermal analysis

Adjusting sink Location to Reduce End-to-End Delay in Low-Duty-Cycle Wireless Sensor Networks

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Journal of Electronic Science and Technology 2015年第1期13卷 20-26页

作者： Yu-Yuan Lin Kuo-Feng Ssu Hau-Yu Chiang Institute of Computer and Communication Engineering National Cheng Kung University Department of Electrical Engineering National Cheng Kung University Data Systems Consulting Co. Ltd

Low-duty-cycle mechanisms can reduce the energy consumption significantly in wireless sensor networks（WSNs）. Sensors stay dormant most of the time to save their energy and wake up based on their needs. However, such a technique, while prolonging the network lifetime, sets excessive challenges for reducing the end-to-end（E2E） delay within the network. In this paper, the centralized cluster-based location finding（CCLF） algorithm is proposed to reduce the high latency in low-duty-cycle WSNs by finding a suitable position for the sink. The algorithm is mainly composed of three steps： a） the cluster construction, b） the fast look-up table（FLU-table） construction, and c） the sink location decision. The simulation results show that the performance of the CCLF algorithm is significantly similar to that of the optimal algorithm. Moreover, the CCLF algorithm requires less operation time compared with the optimal algorithm.

关键词： Duty cycle latency sink wireless sensor networks

Assessing effects of “source-sink” landscape on non-point source pollution based on cell units of a small agricultural catchment

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Journal of Mountain Science 2019年第9期16卷 2048-2062页

作者： WANG Jin-liang CHEN Cheng-long NI Jiu-pai XIE De-ti GUO Xi LUO Zhi-jun ZHAO Yue School of Land Resources and Environment Jiangxi Agriculture University Nanchang 330045 China School of Resources and Environment Southwest University Chongqing 400715 China Research Center for Development and Utility of Unique Resources in the Wulingshan Region Yangtze Normal Universityf Fuling 408100 China

Ascertaining the relationship between "source-sink" landscape and non-point source(NPS) pollution is crucial for reducing NPS pollution, however, it is not easy to realize this target on cell unit scale. To reveal the relationships between "sourcesink" landscape and NPS pollution based on cell units of a small catchment in the Three Gorges Reservoir Region(TGRR), the runoff and nutrient yields were simulated first by rainfall events on a cell unit scale based on the Annualized AGricultural Non-Point Source Pollution Model(AnnAGNPS). Landscape structure and pattern were quantified with "sourcesink" landscape indicators based on cell units including landscape area indices and locationweighted landscape indices. The results showed that:the study case of small Wangjiagou catchment highlighted a good prediction capability of runoff and nutrient export by the AnnAGNPS model. Throughout the catchment, the spatial distribution trends of four location-weighted landscape indices were similar to the trends of simulated total nitrogen(TN) and total phosphorus(TP), which highlighted the importance of spatial arrangement of "source" and "sink" landscape types in a catchment when estimating pollutant loads. Results by Pearson correlation analysis indicated that the location-weighted landscape index provided a more comprehensive account of multiple factors, and can better reflect NPS-related nutrient loss than other landscape indices applied in single-factor analysis. This study provides new findings for applying the "source-sink" landscape indices based on cell units in small catchments to explain the effect of "source-sink" landscape on nutrient export based on cell unit, and helps improve the understanding of the correlation between "source-sink" landscape and NPS pollution.

关键词： Nutrient load Non-point source pollution Source sink Landscape index Small catchment

Dynamics Analysis of Nonlinear Energy sink for Metal-Rubber Vibration Absorber

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Journal of Harbin Institute of Technology(New Series) 2017年第5期24卷 39-45页

作者： Xianren Kong Huai Xiong Yuan Liu Zhenguo Yang Research Center of Satellite Technology Harbin Institute of Technology

Recent advances in the application of the nonlinear energy sink under a sinusoidal excitation make it possible to investigate metal-rubber vibration absorber. To provide such a vibration absorber for the integrated spacecraft platform,we analyze the targeted energy transfer of the simplified model with nonlinear energy sink using the complex-variables averaging method. Theoretical study shows two quasi-periodic responses that are essentially different in this nonlinear system. The steady-state response which is one of two quasi-periodic responses is caused by the linear instability of system,and another one appears as a result of the nonlinear normal modes between the linear and nonlinear oscillators,resulting from the energy transfer of different oscillators,and it can be used to vibration absorber. Secondly,this paper also discusses the performance of the proposed nonlinear absorber by using the phase portraits. All conclusion derived by the analytic model is verified numerically and the results are consistent with numerical simulations.

关键词： nonlinear energy sink targeted energy transfer metal-rubber vibration absorber complex-variables averaging methods

Thermal Modeling of Thermosyphon Integrated Heat sink for CPU Cooling

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Journal of Electronics Cooling and Thermal Control 2011年第2期1卷 15-21页

作者： A. Shanmuga Sundaram Anirudh Bhaskaran 不详

A thermal model has been developed to study the thermal behavior of Thermosyphon integrated Heat sink during CPU cooling. An Indirect cooling module has been experimentally studied and analyzed under steady state condition for both natural and forced convection. The thermal model is employed to determine the actual heat transfer and the effectiveness of the present model and compared it with the conventional cooling method and found that there is an appreciable improvement in the present model.

关键词： Thermosyphon Heat sink Effectiveness Conventional Cooling Method

Magnetic Field and Thermal Radiation Effect on Heat and Mass Transfer of Air Flow near a Moving Infinite Plate with a Constant Heat sink

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World Journal of Mechanics 2015年第12期5卷 235-248页

作者： S. M. Arifuzzaman Sajal Kumar Dhali Md. Abul Kalam Azad Bibhuti Roy Mathematics Discipline Khulna University Khulna Bangladesh Computer Science and Engineering Discipline Khulna University Khulna Bangladesh

Analytical investigation on a combined heat and mass transfer of air flow near a continuously moving infinite plate with a constant heat sink is performed in the presence of a uniform magnetic field. To observe the thermal radiation and Soret effect on the flow, thermal radiation and thermal diffusion term are added in energy and concentration equations. A flow of model is established by employing the well known boundary layer approximations. In order to obtain non-dimensional system of equations, a similarity transformation is applied on the flow model. Perturbation technique is used as main tool for the analytical approach. The numerical values of flow variables are computed by a FORTRAN program. The obtain numerical values of fluid velocity, temperature and species concentration are drawn for the different values of various parameters. To observe the effects of various parameters on the flow variables, the results are discussed in detailed with the help of graph.

关键词： Viscous Fluid MHD Thermal Radiation Heat sink Chemical Reaction Soret Effects